Method and means for placing artificial seaweed

ABSTRACT

A method and means for placing &#39;&#39;&#39;&#39;artificial seaweed&#39;&#39;&#39;&#39; in place on a particulate floor of a body of water comprises releasably securing the lower end of a fluid conduit to an anchoring means, such as a dish-shaped plastic article, having strands of buoyant, water-resistant elongated flexible strands secured thereto and having fluid outlet orifices communicating with said fluid conduit and directed against said particulate floor; forcing fluid through said conduit while said anchoring means is adjacent to or resting on or pressed against said floor to displace particulate matter; causing said anchoring means to settle into the resulting cavity as it is formed; discontinuing flow of said fluid; permitting particulate to settle over said anchoring means; and disconnecting said conduit.

United States Patent Edwards 1 5] Mar. 14, 1972 [54] METHOD AND MEANS FOR PLACING 3,299,640 1/1967 Nielsen ..61/3

ARTIFICIAL SEAWEED Primary Examiner-Jacob Shapiro [72] Inventor: Keith W. Edwards, 47 Station Road, Atmmey Mal-tin Baer and Joseph w Brown Thames Ditton, England [22] Filed: Jan. 22, 1970 [571 ABSTRACT [21] APPL No; 5 001 A method and means for placing artificial seaweed in place on a particulate floor of a body of water comprises releasably securing the lower end of a fluid conduit to an anchoring [30] Fore gn Application y 818 means, such as a dish-shaped plastic article, having strands of buoyant, water-resistant elongated flexible strands secured Jan. 22, 1969 Great Britain ..3,579/69 thereto and having fluid outlet orifices communicating with said fluid conduit and directed against said particulate floor; 'g forcing fluid through said conduit while said anchoring means [58] Field 2 53 1/7 1 7 2 is adjacent to or resting on or pressed against said floor to displace particulate matter; causing said anchoring means to settie into the resulting cavity as it is formed; discontinuing flow [56] References cued of said fluid; permitting particulate to settle over said anchor- UNITED STATES p ATENTS ing means; and disconnecting said conduit.

1,409,140 3/ 1922 Bignell ..61/53.74 X 5 Claims, 2 Drawing Figures PAIENTEDMAR 14 I972 FIG. I

ltllll rllilflli' m 5 FIG. 2

INVENTORI KEHTH W. EDWARDS m1: 5 6m HIS ATTORNEY METHOD AND MEANS FOR PLACING ARTIFICIAL SEAWEEI) The invention relates to a method of anchoring artificial seaweed comprised of assemblages of buoyant, water-resistant, elongated, flexible elements of synthetic polymer, secured to anchoring bodies, to a sandy or other particulate floor underneath a body of water.

Artificial seaweed installed underwater as a means of controlling the migration of materials in seas, rivers or other bodies of water to protect the underwater floor or the coast along the water against erosion, or to promote the deposition of sand, is described, for example, in US. Pat. No. 3,299,640 to Nielsen.

ln order to ensure satisfactory performance of the artificial seaweed over a long period, it should be firmly anchored to the floor underneath the water. For this purpose, the seaweed can be connected to anchoring bodies such as concrete blocks or steel cables, which are laid on the sea floor and by their weight maintain the seaweed at the desired place. Since the synthetic elongated seaweed elements, generally referred to herein as strands, themselves have a weight less than water and also because the seaweed is commonly to be used at places with strong underwater currents, a rather great volume of anchoring material is required to ensure adequate anchoring of the seaweed. Therefore, even with the use of cheap weighting materials, the costs of an artificial seaweed project may surpass an acceptable level, and even with the use of heavy anchoring bodies there remains the possibility that under severe conditions, such as in a storm, the seaweed is displaced.

The anchoring bodies may sink to some extent into the sea floor under their own weight, whereby improved anchorage of the seaweed is obtained. This situation is reached only after the seaweed has remained unsatisfactorily anchored for quite some time, and in the initial period of its useful life the seaweed is more vulnerable to displacement or lifting than after this period when some deposit of sand has been formed at the foot of the seaweed. Furthermore, because of rapidly increasing resistance offered by the sea floor on sinking of an anchoring body therein, the final depth of the anchoring bodies in the floor is very limited, so that the anchoring bodies are not securely retained by the floor.

It is therefore an object of the invention to provide a simple yet effective manner of anchoring artificial seaweed to a par ticulate floor underneath a body of water, in which a high anchoring force is obtained with the use of small-sized and lightweight anchoring means.

According to the invention, a method of anchoring artificial seaweed formed of assemblages of buoyant, water-resistant, elongated, flexible, elements secured to anchoring bodies, to a particulate floor underneath a body of water, comprises releasably connecting a lower end of a fluid conduit to an anchoring body of seaweed, lowering the lower end of the fluid conduit with the anchoring body connected thereto to said particulate floor, forcing a fluid through the conduit for discharge under the anchoring body, to displace particulate matter from beneath the anchoring body and thereby generate a cavity, causing the anchoring body to settle into said cavity as it is formed, discontinuing the flow of fluid and disconnecting and removing the conduit from the anchoring body.

The seaweed can be laid from a barge or other vessel. The anchoring bodies are releasably connected to the lower end of the fluid conduit, which is usually a rigid tube, by coupling means allowing the tube to be withdrawn from the anchoring body after the latter has reached its desired depth in the sea floor. A suitable coupling means is a bayonetcatch. Alternatively, the tube may have a threaded lower end which is screwed in or around a correspondingly threaded tubular member of the anchoring body. In these cases the anchoring body is connected to or disconnected from the tube by rotation of the tube relative to the anchoring body. Other possibilities for releasably connecting the anchoring body to the tube are to clamp these parts together or to join them with snap acting means. The anchoring body can also be formed with a tubular member which fits tightly and telescopically in or around the lower end of the tube so that the anchoring body is held to the tube by friction during the time it is lowered through the water and thereafter can be released by pulling slightly at the upper end of the tube. The anchoring body, once buried in the sea floor, is capable of resisting considerable rotational or pulling forces, allowing the tube to be removed from the anchoring body, once the latter has been installed in the sea floor, without difficulties.

Preferably the anchoring bodies are shaped so as to allow their easy penetration into the sea floor but to resist their withdrawal therefrom. The anchoring body is suitably formed as a dish having a tubular member for connection to the tube or other fluid conduit. The dish is preferably a cone, having the tubular member secured to the edges of a central opening therein.

The anchoring body is preferably made of a thermoplastics material, such as polyvinylchloride or polypropylene. The body is suitably produced as an integral unit, as by injection molding.

After the anchoring body has been connected to the tube, both are lowered into and through the water until the anchoring body has reached the floor underneath the sea or other body of water. This can be learned from a sudden increase in the resistance experienced when lowering the tube if a relatively rigid tube is employed, or from slackening observed in a flexible tube used with a relatively heavier anchor. Water is then pumped through the tube for discharge at the sea floor underneath the anchoring body.

The water flow displaces the particulate material, thereby allowing the anchoring body to be sunk into the resulting cavity in the sea floor to a considerable depth with little or no force being required to penetrate the floor.

The water can be discharged directly from the lower end of the tube into the surrounding body of water. Alternatively, the water from the tube flows through a tubular member of the anchoring body to which the tube is connected and from there is discharged through openings into the surrounding body of water. For this purpose the lower end of the tube or the anchoring body may be provided with a series of small discharge openings. Normally, the water need not be forced through these openings with great pressure. Normally, a pressure of 2 or 3 kg/cm. above the hydrostatic pressure at the level of the sea floor will be found sufficient, although if desired a higher pressure may be applied.

While water is being pumped down the tube the latter is lowered to sink the anchoring body into the sea floor. lf the tube extends above the water surface, a. workman on the barge may direct the tube downward by hand.

The anchoring body is preferably pressed down against the seafloor and caused to settle into the cavity by pressure transmitted through rigid tubular conduit, but the desired force may also be due to the weight of the anchoring means or to a weight permanently or releasably attached to the anchoring means.

The tube may be provided with weight means to facilitate lowering the anchoring body or the tube may be lowered or guided 'by mechanical means, but this will generally be unnecessary. After the anchoring body has been sunk to the required depth in the sea floor, for example half a meter, which maytakelessthan 1 minute, the flow of water through the tube is stopped. Preferablythe tube is of sufficient length to have its upper end still above water at this moment, so that the depth of penetration of the anchoring body in the sea floor can be easily controlled on the barge by checking the distance over which the upper end of the tube has been lowered.

When the pumping operation is stopped, the soil around the anchoring body starts settling quickly, thereby firmly anchoring this body to the floor. The tube can then be disconnected from the anchoring body by rotation and/or upward movement of the tube at its upper end. The tube is then raised to the surface of the water and the operations: are repeated for sinking another anchoring body in the sea floor.

It is possible to anchor a plurality of anchoring bodies simultaneously side-by-side with the aid of a plurality of tubes or with a single tube having as many branched ends as there are anchoring bodies to be lowered. In this manner, a curtain type of seaweed having its anchoring bodies pre-connected thereto with a spacing less than the depth of the body of water can be anchored, thereby also achieving great savings in time needed to install the seaweed on the sea floor.

One embodiment of the invention will now be described with reference to the accompanying diagrammatic drawing, in which FIG. 1 illustrates seaweed being anchored by the method of the invention; and

FIG. 2 shows on type of an anchoring body for the seaweed.

Starting with FIG. 2, an anchoring body is shown comprising a cone-shaped member 11 and a tubular member 12. The tubular member 12 is coaxial with the cone member 11 and is secured to the edges of a central opening therein. Preferably members 11 and 12 are formed as one integral part. Seaweed strands 14 are secured to the anchoring body by any suitable means, as between a clamping ring 13 and the peripheral edge of cone member 11 on which the clamping ring is clamped or snapped. The strands 14 are made of synthetic material and have a density less than water so that underwater the strands will assume an upright position. Suitable the strands 14 are thermoplastic film strips, or foamed thermoplastic filaments. A preferred form of low density strands, formed from foamed polypropylene strands which are produced by extrusion using a volatile liquid such as pentane as a foaming agent and which are subsequently stretched to obtain thin bands, are disclosed in copending application Ser. No. 778,757, filed Nov. 25, 1968. The length of the strands 14 can suitably vary between 50 cm. and several meters, depending on use and local circumstances. It is to be understood that strands are attached around the full circumference of cone member 11.

To anchor the anchoring body to a sea floor it is connected to the lower end of a tube 15. For this purpose the wall of tubular member 12 of the anchoring body is provided with a slot 16 which receives a dowel 17 connected to the tube 15. The slot 16 and dowel 17 form elements of a bayonet-catch allowing the tube to be connected to and disconnected from the anchoring body. Tube fits slidingly-within tubular member 12 and projects below this member. In the wall of the projecting portion 19 of tube 15 a number of small orifices 18 have been drilled for the lateral discharge of fluid from the tube 15. The bottom end 19 of tube 15 below the orifices 18 is closed with an end plate 20 in which also one or more orifices 21 have been drilled for the downward discharge of fluid from the tube 15.

Anchoring body 10 is lowered by tube 15 from a barge 22 (FIG. 1) floating on a sea or other body of water 23 at an anchored position. After anchoring body 10 has reached the bottom of the water as can be judged from a strongly increasing resistance on lowering the relatively rigid tube, water is forced into the upper end of tube 15 by a pump mounted on the barge. The water pumped down the tube flows through orifices 18 and 21 of the tube and creates turbulences in the water under the anchoring body, whereby the particulate material of the sea floor 24 is displaced and mixed with water and may start behaving like a fluid. The anchoring body can then be easily lowered into the sea floor, while the flow of water down the tube is maintained, until the body has reached the desired depth, varying from 20 cm. to 1 meter or more. Pumping of water is then stopped, whereupon the material of the sea floor settles around and upon the anchoring body. The anchoring body is thereby firmly secured to the sea floor, whereupon the tube is rotated and lifted to disengage the dowel 17 from the slot 16. The tube is then raised until its lower end is above the water, allowing another anchoring body to be connected thereto whereupon the operations are repeated.

In a test to demonstrate the effectiveness of the anchoring obtained by the method of the invention, a polyvinylchloride anchoring body was used of the design illustrated in FIG. 2. The outside diameter of the cone member was l 10 mm. and its height was 25 mm. The wall thickness throughout the anchoring body was 4 mm. The tube on which the anchoring body was lowered was a polyvinylchoride tube of 16 mm. outside diameter. The lower end of the tube was provided with six lateral orifices and the end plate at the bottom end of the tube with one centrally located orifice, all orifices having a diameter of 3 mm. Water was pressed through these orifices at a pressure of some 2 kg./cm. above the hydrostatic pressure at this level until the anchoring body had been lowered 50 cm. deep into a sand floor underneath the water. After the tube had been removed from the anchoring body a force of I50 kg. was necessary to lift the anchoring body from the sand.

The method of this invention is particularly adapted for use in sandy sea floor, but may also be applied where the floor consists of other particulate matter that can be displaced by water, e.g., pebbles or mud. It is obviously not designed for use on monolithic floors.

While the preferred fluid for use in this invention is water, the desired effect can also be obtained by use of other fluids, including air. I

Other modifications of the described embodiments can be made within the scope of this invention. The fluid outlet holes may be in the bottom of the anchor device instead of in the removable tube. Anchoring devices of a variety of shapes may be employed, for example, the element of the anchor to which the buoyant strands are attached may be linear rather than circular.

Iclaim:

1. Method of anchoring buoyant, elongated, flexible synthetic polymer strands which are secured to an anchoring body, to a particulate floor under a body of water, comprising releasably connecting the lower end of a fluid conduit to said anchoring body to which the polymer strands are attached, lowering the lower end of the fluid conduit with the anchoring body connected thereto to said floor, forcing a fluid through said conduit and out the lower end thereof to said floor under the anchoring body to displace particulate matter and thereby generate a cavity, causing said anchoring body to settle into said cavity as it is formed, discontinuing the flow of fluid, and disconnecting and removing the conduit from the anchoring body.

2. The method according to claim 1 in which the lower end of said fluid conduit is releasably connected to a tubular member of said anchoring body in fluid communication therewith.

3. The method according to claim 1 in which said anchoring body is forced against said particulate floor by pressure transmitted through rigid tubing forming said conduit.

4. Method of anchoring buoyant elongated, flexible, synthetic polymer strands secured to an anchoring body, to a particulate floor under a body of water, comprising releasably connecting above the body of water the lower end of a fluid conduit to said anchoring body, lowering the lower end of the fluid conduit with the anchoring body connected thereto through the body of water to near said floor, further lowering the lower end of the fluid conduit and the anchoring body into the said floor while simultaneously forcing a fluid through said conduit and out the lower end thereof to said floor under the anchoring body to displace particulate matter and thereby generate a cavity, causing said anchoring body to settle into said cavity as it is formed, discontinuing the flow of fluid, disconnecting the conduit from the anchoring body after sufficient particulate matter has settled over said anchoring body to maintain it in place, and raising the conduit.

5. Method of anchoring buoyant elongated, flexible, synthetic polymer strands secured to an anchoring body which is sufficiently non-buoyant to overcome the buoyancy of the polymer strands, to a particulate floor under a body of water, comprising releasable connecting above the body of water the lower end of a fluid conduit to said anchoring body so that the lower end of the conduit is secured to the anchoring body cavity, causing said anchoring body to settle into said cavity as it is formed, discontinuing the flow of fluid, disconnecting the conduit from the anchoring body after sufficient particulate matter has settled over said anchoring body to maintain it in place, and raising the conduit. 

1. Method of anchoring buoyant, elongated, flexible synthetic polymer strands which are secured to an anchoring body, to a particulate floor under a body of water, comprising releasably connecting the lower end of a fluid conduit to said anchoring body to which the polymer strands are attached, lowering the lower end of the fluid conduit with the anchoring body connected thereto to said floor, forcing a fluid through said conduit and out the loWer end thereof to said floor under the anchoring body to displace particulate matter and thereby generate a cavity, causing said anchoring body to settle into said cavity as it is formed, discontinuing the flow of fluid, and disconnecting and removing the conduit from the anchoring body.
 2. The method according to claim 1 in which the lower end of said fluid conduit is releasably connected to a tubular member of said anchoring body in fluid communication therewith.
 3. The method according to claim 1 in which said anchoring body is forced against said particulate floor by pressure transmitted through rigid tubing forming said conduit.
 4. Method of anchoring buoyant elongated, flexible, synthetic polymer strands secured to an anchoring body, to a particulate floor under a body of water, comprising releasably connecting above the body of water the lower end of a fluid conduit to said anchoring body, lowering the lower end of the fluid conduit with the anchoring body connected thereto through the body of water to near said floor, further lowering the lower end of the fluid conduit and the anchoring body into the said floor while simultaneously forcing a fluid through said conduit and out the lower end thereof to said floor under the anchoring body to displace particulate matter and thereby generate a cavity, causing said anchoring body to settle into said cavity as it is formed, discontinuing the flow of fluid, disconnecting the conduit from the anchoring body after sufficient particulate matter has settled over said anchoring body to maintain it in place, and raising the conduit.
 5. Method of anchoring buoyant elongated, flexible, synthetic polymer strands secured to an anchoring body which is sufficiently non-buoyant to overcome the buoyancy of the polymer strands, to a particulate floor under a body of water, comprising releasably connecting above the body of water the lower end of a fluid conduit to said anchoring body so that the lower end of the conduit is secured to the anchoring body below its lower end, lowering the lower end of the fluid conduit with the anchoring body connected thereto through the body of water to near said floor, further lowering the lower end of the fluid conduit and the anchoring body into the said floor while simultaneously forcing a fluid through said conduit and out the lower end thereof to said floor under the anchoring body to displace particulate matter and thereby generate a cavity, causing said anchoring body to settle into said cavity as it is formed, discontinuing the flow of fluid, disconnecting the conduit from the anchoring body after sufficient particulate matter has settled over said anchoring body to maintain it in place, and raising the conduit. 